Improvement in fire-bridges for sfham-boiler furnaces



R. K. McMURRAY. FIRE-BRIDGE FOR STEAM-BOILER FURNACES.

No. 194,780. Patented Sept. 4,1a-7'1f ATTORNEY v To all whom it may concern Be it known that I, ROBERT E. MCMUR-; L-BAY, of -West New Brighton, in the county of :Richmond and State of New York, have in- UNITED STATES. PATENT ROBERT K. MoMURRAY, 0F WEST NEW.BRIGHTON, NEW YORK.

IMPROVEMENT m FiiaE-BRibGEs FbR 'SiEAM BOILER 'FuRNAeEs.

Specification forming part of Letters Patent No. 194,786, dated September 4, 1877; application filed June 11; 1877. l

vented certain new and useful Improvements in Fire'Bridges for Steam-Boiler Furnaces, of

which the following is aspecificationt.

The object of my invention is to provide effective means for economizing the consumption of fuel in the furnaces of steamfboilers,

and for the. prevention of smoke by the 'ad- 1 mission of a proper supply of'heated air to the gases evolved by combustion; and, fur-1 'ther, to efi'ect a reduction in the time and ex- .p'ense heretofore required for the renewal and repair of bridge-walls employed in boiler-settings.

a To these ends my improvements consist in combining, with the furnace and combustionchamber of a steam-boiler, a. hollow metallic fire-bridge, formed of a series of plates united together and restingupon the top of a bridgewall of the ordinary construction, without being embedded therein, into which hollow bridge fresh air in properlygraduated proportions is introduced, and within which it is heated to a temperature approximating to that of the gases escaping from the furnace, and is thence delivered, in a minuteIy-diVided condition, to said gases as they enter the com .bustion-chamber. My improvements further consist in such construction of said fire-bridge as to provide ample resistance against blows or shocks-and the effects of expansion and contraction, as well as to render it capable of being readily and quickly removed from its position in the setting, renewed or repaired at a comparatively slight expense,- and replaced in position for further operation.

The improvements claimed are hereinafter fully set forth.

In the accompanyingdrawings, Figure l is a vertical longitudinal central section through the setting .of. a return tubular stationary boiler with my improvements applied; Fig. 2, a transverse section through the fire-bridge at the line 1 1 ofFigi 3; Fig. 3, a longitudia plan view of one of th'edispersing-plates detached. a v

To carry out my invention I provide a hollow metallic fire-bridge, preferably composed of cast-iron sections, the 1 width of which firebridge is about equal to thefthickness of the bridge-wall upon which itis set, audits length slightly greater than the inside widthof the furnace and combustion-cham ber,'so as to project into eachof the side walls thereof for a distance of, say, one inch. The fire-bridge consists of three principal members-to wit, a v

fire-plate, A, a back or base plate, B, and a dispersing-plate, G-j-which areconstructed and connected substantially as follows: The plate A, whichI designate as the fire-plate by reason of the fact that it is designed to receive the direct heat of the fire, is corrugated throughout its entire length so as to increase its strength and allow for expansion and contraction under changes of temperature, and its thickness is sufficientl y great, say about threefourths of an inch, to adequately resist blows from a slice-bar, to which, from its position, it is necessarily exposed. It is provided with a light bottom flange, a, which rests upon the bridge-wall, and thence rises vertically for about two-thirds of its height, at which point it is inclined at an angle of forty-five-degrees, or thereabout, extending to a horizontal top surface, being longitudinally corrugated, as before stated, at, all points except upon its bottom flange. The bottom flange might be made separate, if preferred,- and fitted between the fire-plate and back plate, or cast upon the back plate; but I deem the arrangement shown more desirable, as affording a moreuniform distribution of metal in the several portions of the bridge. The bottom plate B is a light angular plate, substantially conforming, in: the relative position of three of its sides, to the plate A, and, in addition,-projecting, downwardly from: its upper surface in reverse direction. to, but at a similar angle with, its rising incline, and terminating .in a horizontal flange or foot, b. The plates A and B are connected bybolts a pal sectionat theline 2 2 of Fig. 2; Fig. 4, a passing through thimbles or distance-pieces,

plan or top view of the fire-bridge, and 5,

a, so as to form a hollow case or trough, and adispersing or diffusing-plate, O, perforated throughout its entire length with numerous small orifices, is inserted in lips or grooves formed in the edges of the top surface of the fire-plate A and the bottom flange b of the plate B, respectively. The connecting-bolts a are arranged in two series, one vertical, passing through the upper surfaces of the plates A and B, and the other horizontal, and as near as convenient to their lower edges. A series of air-supply openings, 1), are formed in the plate B, as near as practicable to its base, above which a horizontal deflecting-flange, 12, extends along the side of the plate B, adjacent to the plate A, the width of said flange being about one-half inch less than the distance between the two plates, and the edge of the flange being curved correspondingly with the corrugations of the plate A, so as .to maintain a uniform width of opening between the flange and fire-plate for the entire length of the bridge. In practice the dispersing-plate may be formed in separate sections, as shown, instead of in a single piece, both for greater convenience in casting and to reduce the expense of renewal in the event of breakage.

In the application of my improved firebridge toa boiler-setting it is placed upon an ordinary brick bridge-wall, without being embedded therein, the lower edge of the fireplate A being slightly below the level of the grate-bars, and its ends are closed by the side walls of the setting or by metal plates fitted therein, the latter plan being preferable; as in such case, by the removal of the plate at either end, the fire-bridge may be removed, whenever desired, by drawing it out longitudinally through the opening in the side wall, without disturbing any of the brickwork of the setting, and it can be replaced in a similar manner. lf, however, its ends be closed by the side walls, it is only necessary, for the'purpose ofremoval, to take out a sufficient number of bricks at one end to form an opening large enough for its withdrawal, and this can be done in a very short time, and without the necessity of awaiting the cooling down of the furnace and combustion-chamber. This capability of readyremoval and replacement for renewal or repair constitutes an important feature of my improvements as compared with the ordinary brick bridge-walls, or with devices embedded therein or in the setting. A register or valve of any suitable which is admitted thereto at one or both ends beneath the back plate, enters the space between the back plate and fire-plate through the supply-openings b and is deflected by the flange 12 against the heated surface of the fire-plate, and passes upward along the space between the two plates. In its traverse therein it is heated by its impingement upon the entire inner surface of the hot fire-plate, and is introduced in a minutely-divided condition into the combustion-chamber at a temperature closely approximating that of the gases escaping from the furnace, with which it mingles immediately upon their passage over the top of the bridge, thoroughly oxidizing the inflowing carbonic oxide, and efiecting a complete combustion, with a corresponding economy of fuel and prevention of smoke. Its advantage, moreover, in durability over the ordinary fire-brick bridge will be apparent to the practical steam-engineer, inasmuch as the fire-plate only is exposed to the direct action of the fire, and, from its material and form of construction, is possessed of greater power of resistance to the destructiveinfluences brought upon it.

In the event of repair, the entire bridge can be removed, a new plate be inserted, and the bridge replaced in position with much less labor and expense, and with far greater expedition, than is practicable in the case of a brick bridge-wall.

I am aware that hollow fire-bridges having an internal air passage or passages and a series of openings or perforations for the supply of air to a combustion-chamber have been heretofore known; and I do not, therefore, broadly claim such device, either per se or in combination.

I claim as my invention and desire to secure by Letters Patent- 1. The combination, in a steam-boiler setting, of a furnace, a combustion-chamber comm unicating therewith, an intermediate bridgewall, and a series of plates connected together to form a hollow metallic fire-bridge, which rests on, without being embedded in, the bridge-wall, and is removable therefrom through an opening in the side wall of the setting, substantially as set forth. I

2. The combination, in a fire-bridge for steam-boiler furnaces, of a corrugated fireplate, a back plate connected thereto, and provided with a series of air-supply openings, and a perforated diffusing-plate, substantially as set forth.

3. The combination, in a fire-bridge for steam-boiler furnaces, of a fire-plate, a back plate, interposed distance-pieces, and connecting-bolts, substantially as set forth.

4. The combination, with the fire-plate, of a back plate having a series of air-supply openings near its bottom, and a longitudinal deflecting-flange projecting into the space between the fire-plate and back plate above the air-supply openings, and of less width-at all points than the distance between said plates, substantially as set forth.

5. The combination, substantially as set forth, of a fire-plate, a back plate, and a diffusing-plate, connected together and forming a hollow metallic fire-bridge, which is beveled or inclined in opposite directions toward its top, and is provided with a lower series of airsupply openings and an upper series of airdischarge openings. 7

R. K. MOMURRAY. Witnesses:

J. SNOWDEN BELL, Tnno. H. BABOOGK. 

